The invention relates to a device of quartz glass for receiving or holding work pieces to be heated in a furnace.
In methods of purifying and sintering ceramic green bodies, such as are required, for example, for the manufacture of quartz glasses of high purity, which are required, for example, as substrate tubes for the manufacture of optical wave guides or as bulb glass for the manufacture of halogen or gas discharge lamps, or of purifying and sintering ceramic green bodies, such as are required, for example, for the manufacture of electronic elements, device parts in the form of working tubes, in which the green body to be purified is arranged and through which the purification gas flows, or in the form of holding rods, to which the purified body to be sintered is secured, are used for the heating processes during the purification and the sintering of the green bodies.
A purification and sintering method for such green bodies is proposed, for example, in German Patent Application No. P 36 19 510.3.
Such devices advantageously consist of quartz glass. These devices are inserted into an electrically heated furnace and are used at temperatures of at least up to 1500.degree. C.
At purification temperatures above 800.degree. C., a strongly increasing part of the furnace heat is transported by radiation to the furnace ends. With the use of quartz glass for the said devices, a large part of this radiation heat is passed within the quartz glass by multiple total reflection on account of the favourable transmission properties of quartz glass and at this area the radiation can emanate again at perpendicular intersection surfaces. The problem appears therefrom that further device parts, such as sealing rings of, for example, natural or synthetic caoutchouc, or metallic securing parts, connected to the devices of quartz glass are strongly heated. This heating by radiation cannot be reduced by cooling from the outside, for example by means of air or water. Due to the great differences between the refractive indices of quartz glass and air, the radiation once coupled in the hot furnace zone into a device part of quartz glass is passed as well as radiation in, for example, an optical wave guide and this radiation does not emanate even at bends.